Data staging area

ABSTRACT

An illustrative embodiment of a computer-implemented process for managing a staging area creates the staging area for identified candidate cold objects, moves the identified candidate objects into the staging area, tracks application access to memory comprising the staging area and determines whether frequency of use information for a specific object exceeds a predetermined threshold. Responsive to a determination that the frequency of use information for the specific object exceeds a predetermined threshold, move the specific object into a regular area and determine whether a current time exceeds a predetermined threshold. Responsive to a determination that the current time exceeds a predetermined threshold, the computer-implemented process moves remaining objects from the staging area to a cold area.

BACKGROUND

1. Technical Field

This disclosure relates generally to memory management in a dataprocessing system and more specifically to managing data staging in thedata processing system.

2. Description of the Related Art

As several different performing tiers in memory become more prevalentthe underlying physical memory in computer systems becomes less uniform.Moreover, with the emergence of cloud computing technologies use ofvirtualized environments is growing in an effort to utilize machines toa fullest capacity with respect to processors and memory.

Application memory space is typically spread across several differentunderlying physical memory implementations, each potentially having adifferent access speed. Thus, there is a strong need for distributingapplication data in an access frequency conscious manner. Placing mostfrequently accessed, or more popular, data on a fastest physical memoryensures optimal application performance, reduces power consumption andallows for a highest level of hardware utilization.

To address the challenge several data access frequency detection methodshave been developed. Combining a data access frequency detection methodwith a memory management system, such as a garbage collector associatedwith a virtual machine of a managed runtime, results in an ability tointelligently distribute data associated with an application in a tieredmemory environment. Better distribution typically improves overall dataaccess times of the application.

However, perfectly accurate data access frequency detection has a verylarge negative impact on application performance. The data accessfrequency detection methods must therefore sacrifice a certain level ofaccuracy to have a lower runtime overhead. Reduced accuracy typicallycauses certain pieces of very frequently accessed data to be missed by apopularity detection process. The movement of even a few highly populardata items (or objects) to a slower form of memory may greatly lower theperformance of the application.

SUMMARY

According to one embodiment, a computer-implemented process for managinga staging area creates the staging area for identified candidate coldobjects, moves the identified candidate objects into the staging area,tracks application access to memory comprising the staging area anddetermines whether frequency of use information for a specific objectexceeds a predetermined threshold. Responsive to a determination thatthe frequency of use information for the specific object exceeds apredetermined threshold, move the specific object into a regular areaand determine whether a current time exceeds a predetermined threshold.Responsive to a determination that the current time exceeds apredetermined threshold, the computer-implemented process movesremaining objects from the staging area to a cold area.

According to another embodiment, a computer program product for managinga staging area comprises a computer recordable-type media containingcomputer executable program code stored thereon. The computer executableprogram code comprises computer executable program code for creating thestaging area for identified candidate cold objects, creating the stagingarea for identified candidate cold objects, computer executable programcode for moving the identified candidate objects into the staging area,computer executable program code for tracking application access tomemory comprising the staging area, computer executable program code fordetermining whether frequency of use information for a specific objectexceeds a predetermined threshold, computer executable program coderesponsive to a determination that the frequency of use information forthe specific object exceeds a predetermined threshold for moving thespecific object into a regular area, computer executable program codefor determining whether a current time exceeds a predetermined thresholdand computer executable program code responsive to a determination thatthe current time exceeds a predetermined threshold, for moving remainingobjects from the staging area to a cold area.

According to another embodiment, an apparatus for managing a stagingarea comprises a communications fabric, a memory connected to thecommunications fabric, wherein the memory contains computer executableprogram code, a communications unit connected to the communicationsfabric, an input/output unit connected to the communications fabric, adisplay connected to the communications fabric and a processor unitconnected to the communications fabric. The processor unit executes thecomputer executable program code to direct the apparatus to create thestaging area for identified candidate cold objects, create the stagingarea for identified candidate cold objects, move the identifiedcandidate objects into the staging area, track application access tomemory comprising the staging area, determine whether frequency of useinformation for a specific object exceeds a predetermined threshold,responsive to a determination that the frequency of use information forthe specific object exceeds a predetermined threshold, move the specificobject into a regular area, determine whether a current time exceeds apredetermined threshold and responsive to a determination that thecurrent time exceeds a predetermined threshold, move remaining objectsfrom the staging area to a cold area.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

For a more complete understanding of this disclosure, reference is nowmade to the following brief description, taken in conjunction with theaccompanying drawings and detailed description, wherein like referencenumerals represent like parts.

FIG. 1 is a block diagram of an exemplary network data processing systemoperable for various embodiments of the disclosure;

FIG. 2 is a block diagram of an exemplary data processing systemoperable for various embodiments of the disclosure;

FIG. 3 is a block diagram of a memory manager operable for variousembodiments of the disclosure;

FIG. 4 is a block diagram of a memory configuration managed by a memorymanager in accordance with one embodiment of the disclosure;

FIG. 5 is a block diagram of a memory configuration with staging area inaccordance with one embodiment of the disclosure;

FIG. 6 is a block diagram of a memory configuration with staging area inaccordance with one embodiment of the disclosure;

FIG. 7 is a block diagram of a memory configuration with staging area inaccordance with one embodiment of the disclosure;

FIG. 8 is a block diagram of a memory configuration used with a memorymanager in accordance with an illustrative embodiment of the disclosure;

FIG. 9 is a flowchart of a process for managing a staging area inaccordance with various embodiments of the disclosure.

DETAILED DESCRIPTION

Although an illustrative implementation of one or more embodiments isprovided below, the disclosed systems and/or methods may be implementedusing any number of techniques. This disclosure should in no way belimited to the illustrative implementations, drawings, and techniquesillustrated below, including the exemplary designs and implementationsillustrated and described herein, but may be modified within the scopeof the appended claims along with their full scope of equivalents.

As will be appreciated by one skilled in the art, aspects of the presentdisclosure may be embodied as a system, method or computer programproduct. Accordingly, aspects of the-present disclosure may take theform of an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as a “circuit,” “module,” or “system.”Furthermore, aspects of the present invention may take the form of acomputer program product embodied in one or more computer readablemedium(s) having computer readable program code embodied thereon.

Any combination of one or more computer-readable medium(s) may beutilized. The computer-readable medium may be a computer-readable signalmedium or a computer-readable storage medium. A computer-readablestorage medium may be, for example, but not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, or device, or any suitable combination of the foregoing. Morespecific examples (a non-exhaustive list) of the computer-readablestorage medium would include the following: an electrical connectionhaving one or more wires, a portable computer diskette, a hard disk, arandom access memory (RAM), a read-only memory (ROM), an erasableprogrammable read-only memory (EPROM or Flash memory), an optical fiber,a portable compact disc read-only memory (CDROM), an optical storagedevice, or a magnetic storage device or any suitable combination of theforegoing. In the context of this document, a computer-readable storagemedium may be any tangible medium that can contain, or store a programfor use by or in connection with an instruction execution system,apparatus, or device.

A computer-readable signal medium may include a propagated data signalwith the computer-readable program code embodied therein, for example,either in baseband or as part of a carrier wave. Such a propagatedsignal may take a variety of forms, including but not limited toelectro-magnetic, optical or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a computer readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device.

Program code embodied on a computer-readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wire line, optical fiber cable, RF, etc. or any suitable combination ofthe foregoing.

Computer program code for carrying out operations for aspects of thepresent disclosure may be written in any combination of one or moreprogramming languages, including an object oriented programming languagesuch as Java®, Smalltalk, C++, or the like and conventional proceduralprogramming languages, such as the “C” programming language or similarprogramming languages. Java and all Java-based trademarks and logos aretrademarks of Oracle, and/or its affiliates, in the United States, othercountries or both. The program code may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).

Aspects of the present disclosure are described below with reference toflowchart illustrations and/or block diagrams of methods, apparatus,(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer program instructions.

These computer program instructions may be provided to a processor of ageneral purpose computer, special purpose computer, or otherprogrammable data processing apparatus to produce a machine, such thatthe instructions, which execute via the processor of the computer orother programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer or other programmable dataprocessing apparatus to function in a particular manner, such that theinstructions stored in the computer readable medium produce an articleof manufacture including instructions which implement the function/actspecified in the flowchart and/or block diagram block or blocks.

The computer program instructions may also be loaded onto a computer orother programmable data processing apparatus to cause a series ofoperational steps to be performed on the computer or other programmableapparatus to produce a computer-implemented process such that theinstructions which execute on the computer or other programmableapparatus provide processes for implementing the functions/actsspecified in the flowchart and/or block diagram block or blocks.

With reference now to the figures and in particular with reference toFIGS. 1-2, exemplary diagrams of data processing environments areprovided in which illustrative embodiments may be implemented. It shouldbe appreciated that FIGS. 1-2 are only exemplary and are not intended toassert or imply any limitation with regard to the environments in whichdifferent embodiments may be implemented. Many modifications to thedepicted environments may be made.

FIG. 1 depicts a pictorial representation of a network of dataprocessing systems in which illustrative embodiments may be implemented.Network data processing system 100 is a network of computers in whichthe illustrative embodiments may be implemented. Network data processingsystem 100 contains network 102, which is the medium used to providecommunications links between various devices and computers connectedtogether within network data processing system 100. Network 102 mayinclude connections, such as wire, wireless communication links, orfiber optic cables.

In the depicted example, server 104 and server 106 connect to network102 along with storage unit 108. In addition, clients 110, 112, and 114connect to network 102. Clients 110, 112, and 114 may be, for example,personal computers or network computers. In the depicted example, server104 provides data, such as boot files, operating system images, andapplications to clients 110, 112, and 114. Clients 110, 112, and 114 areclients to server 104 in this example. Network data processing system100 may include additional servers, clients, and other devices notshown.

In the depicted example, network data processing system 100 is theInternet with network 102 representing a worldwide collection ofnetworks and gateways that use the Transmission ControlProtocol/Internet Protocol (TCP/IP) suite of protocols to communicatewith one another. At the heart of the Internet is a backbone ofhigh-speed data communication lines between major nodes or hostcomputers, consisting of thousands of commercial, governmental,educational and other computer systems that route data and messages. Ofcourse, network data processing system 100 also may be implemented as anumber of different types of networks, such as for example, an intranet,a local area network (LAN), or a wide area network (WAN). FIG. 1 isintended as an example, and not as an architectural limitation for thedifferent illustrative embodiments.

With reference to FIG. 2 a block diagram of an exemplary data processingsystem operable for various embodiments of the disclosure is presented.In this illustrative example, data processing system 200 includescommunications fabric 202, which provides communications betweenprocessor unit 204, memory 206, persistent storage 208, communicationsunit 210, input/output (I/O) unit 212, and display 214.

Processor unit 204 serves to execute instructions for software that maybe loaded into memory 206. Processor unit 204 may be a set of one ormore processors or may be a multi-processor core, depending on theparticular implementation. Further, processor unit 204 may beimplemented using one or more heterogeneous processor systems in which amain processor is present with secondary processors on a single chip. Asanother illustrative example, processor unit 204 may be a symmetricmulti-processor system containing multiple processors of the same type.

Memory 206 and persistent storage 208 are examples of storage devices216. A storage device is any piece of hardware that is capable ofstoring information, such as, for example without limitation, data,program code in functional form, and/or other suitable informationeither on a temporary basis and/or a permanent basis. Memory 206, inthese examples, may be, for example, a random access memory or any othersuitable volatile or non-volatile storage device. Persistent storage 208may take various forms depending on the particular implementation. Forexample, persistent storage 208 may contain one or more components ordevices. For example, persistent storage 208 may be a hard drive, aflash memory, a rewritable optical disk, a rewritable magnetic tape, orsome combination of the above. The media used by persistent storage 208also may be removable. For example, a removable hard drive may be usedfor persistent storage 208.

Communications unit 210, in these examples, provides for communicationswith other data processing systems or devices. In these examples,communications unit 210 is a network interface card. Communications unit210 may provide communications through the use of either or bothphysical and wireless communications links.

Input/output unit 212 allows for input and output of data with otherdevices that may be connected to data processing system 200. Forexample, input/output unit 212 may provide a connection for user inputthrough a keyboard, a mouse, and/or some other suitable input device.Further, input/output unit 212 may send output to a printer. Display 214provides a mechanism to display information to a user.

Instructions for the operating system, applications and/or programs maybe located in storage devices 216, which are in communication withprocessor unit 204 through communications fabric 202. In theseillustrative examples the instructions are in a functional form onpersistent storage 208. These instructions may be loaded into memory 206for execution by processor unit 204. The processes of the differentembodiments may be performed by processor unit 204 usingcomputer-implemented instructions, which may be located in a memory,such as memory 206.

These instructions are referred to as program code, computer usableprogram code, or computer readable program code that may be read andexecuted by a processor in processor unit 204. The program code in thedifferent embodiments may be embodied on different physical or tangiblecomputer readable storage media, such as memory 206 or persistentstorage 208.

Program code 218 is located in a functional form on computer readablestorage media 220 that is selectively removable and may be loaded ontoor transferred to data processing system 200 for execution by processorunit 204. Program code 218 and computer readable storage media 220 formcomputer program product 222 in these examples. In one example, computerreadable storage media 220 may be in a tangible form, such as, forexample, an optical or magnetic disc that is inserted or placed into adrive or other device that is part of persistent storage 208 fortransfer onto a storage device, such as a hard drive that is part ofpersistent storage 208. In a tangible form, computer readable storagemedia 220 also may take the form of a persistent storage such as a harddrive, a thumb drive, or a flash memory that is connected to dataprocessing system 200. The tangible form of computer readable storagemedia 220 is also referred to as computer recordable storage media. Insome instances, computer readable storage media 220 may not beremovable.

Alternatively, program code 218 may be transferred to data processingsystem 200 from computer readable storage media 220 through acommunications link to communications unit 210 and/or through aconnection to input/output unit 212. The communications link and/or theconnection may be physical or wireless in the illustrative examples. Thecomputer readable media also may take the form of non-tangible media,such as communications links or wireless transmissions containing theprogram code.

In some illustrative embodiments, program code 218 may be downloadedover a network to persistent storage 208 from another device or dataprocessing system for use within data processing system 200. Forinstance, program code stored in a computer readable storage medium in aserver data processing system may be downloaded over a network from theserver to data processing system 200. The data processing systemproviding program code 218 may be a server computer, a client computer,or some other device capable of storing and transmitting program code218.

Using data processing system 200 of FIG. 2 as an example, acomputer-implemented process for managing a staging area is presented.Processor unit 204 creates the staging area for identified candidateobjects, moves the identified candidate objects into the staging area,using storage devices 216, tracks application access to memory ofstorage devices 216 comprising the staging area and determines whetherfrequency of use information for a specific object exceeds apredetermined threshold. Responsive to a determination that thefrequency of use information for the specific object exceeds apredetermined threshold, processor unit 204 moves the specific objectinto a regular area and determines whether a current time exceeds apredetermined threshold. Responsive to a determination that the currenttime exceeds a predetermined threshold, processor unit 204 movesremaining objects from the staging area to a cold area.

An embodiment of the disclosed process provides a typically low overheadstaging area into which seemingly infrequently accessed objects arerelocated for a certain period of time before deciding whether theobjects are truly unpopular and moved to a relatively slower physicalmemory. Creating a staging area enables an opportunity to test datasegregation results of a running system to verify potential consequencesof further movement of data objects. Data, which is deemed frequentlyaccessed through profiling, can be moved back out of the staging area;data that is infrequently accessed can then be moved to a lower tieredstorage layer.

With reference to FIG. 3 a block diagram of a memory manager inaccordance, with various embodiments of the disclosure is presented.Memory manager 300 is an example of an embodiment providing a capabilityto create, and manage utilization of a storage tier within a hierarchyof storage. The storage hierarchy comprises a number of types and speedsof memory ranging between a highest priority and a lowest priority.

Memory manager 300 comprises functional elements including staging areacontroller 302, access pattern tracker 304, detection methods 306 andconfiguration 308. Memory manager 300 and associated components allleverage support from an underlying data processing system such as dataprocessing system 200 of FIG. 2 or a data processing system withinnetwork of data processing system 100 of FIG. 1. Functional elements ofmemory manager 300 may be implemented as discrete physical componentswithin memory manager 300 or as logical units incorporated functionallywithin memory manager 300. Memory manager 300 provides a capability tomanage memory location of objects using a fine-grained process on a perobject basis rather than a more course grained page basis.

Staging area controller 302 provides a capability to create and remove astaging area of memory as well as identify objects as candidates formovement into and out of the staging area. A staging area is a datastructure maintained by staging area controller 302, which is logicallypart of a regular memory area. The staging area may be created from apreviously allocated physical portion of a regular memory area or from aseparate allocation, which is viewed as logically, associated with theregular memory area.

Access pattern tracker 304 provides a set of methods used to identifyand maintain information associated with an application access of dataobjects. The access patterns of objects in the memory, including thestaging area can be tracked using a selected method or a combination ofmethods including traditional read/write barriers, page protectionmechanisms, memory cache/translation look aside buffer (TLB) frequencydata, hardware assisted profiling, and other similar techniques.Information typically maintained in a data structure includes, forexample, access frequency information including an access count that isincremented as a result of an access of a respective object in thememory and a time of last access.

Detection methods 306 provides a set of methods used to identify andrank objects in memory according to associated utilization information.For example a popularity detection method may be selected from the setof methods and used to gather information based on access requests forobjects comprising a set of objects in a regular memory. The popularitydetection method typically ranks each object according to a number ofaccesses as a form of access frequency. A higher ranked object has moredata accesses than a lower ranked object. A time of last access may alsobe used to provide another indication of recent access.

In the current example, using a staging area in combination with apopularity detection method rather than relying entirely on the methodalone enables typical adverse effects of popularity detection errors tobe reduced. The staging area is designed to have much lower data accessoverhead than a slower tiered storage beyond traditional dynamic randomaccess memory (DRAM). The lower overhead implies when an object isaccessed frequently by an application but is missed by the popularitydetection method the overall performance is typically not as adverselyaffected when the object is placed in the staging area compared to whenmoved directly to the slower physical memory.

While the popularity detection method relies on probabilistic orsampling approaches to detect popularity, the staging area detects allactual object access providing a much more accurate representation ofpopularity. Use of the staging area in combination with popularitydetection also enables automatic popularity detection tuning. Thestaging area can be used to programmatically tune parameters of thepopularity detection method by uncovering access patterns in popularobjects missed the popularity detection method.

The staging area with popularity detection adds more flexibility to thepopularity detection method. The staging area provides a degree offlexibility in terms of how stringent the popularity detection algorithmmust be in order to be effective enabling the popularity detectionmethod to be configured to sacrifice more accuracy for the sake ofspeed.

Configuration 308 provides a capability to direct or control theoperation of memory manager 300. Configuration information includes aset of operational information comprising a value for a location (forexample, path information, range of memory) used to create a stagingarea, a size of the staging area including initial size and maximum sizeas well as a time period threshold indicating when to clean the stagingarea. The staging area is typically dynamically created when needed.However, in certain situations a static dedicated staging area may berequired. For example, using certain specialized hardware solutions as aseparate piece of dedicated memory, which is faster than the cold areastorage but also allows access tracking, provides a capability forexclusive use as a staging area. The dedicated memory, for example asolid-state disk, is specifically initialized and maintained for use asthe staging area.

With reference to FIG. 4 a block diagram of a memory configurationmanaged by a memory manager in accordance, with various embodiments ofthe disclosure is presented. Memory 400 is presented in a logical viewwherein portions of the memory depicted need not be implemented as aphysical unit using a same type or speed of memory. Memory 400 is anexample of a memory managed by memory manager 300 of FIG. 3.

Memory 400 comprises a number of portions including regular area 402 andcold area 404. A set of objects is maintained within memory 400 such asobject 406 shown placed within regular area 402, but may be located inother locations equally well within the memory. Currently used objectsare typically located in regular area 402 while infrequently usedobjects tend to migrate to cold area 404.

Memory 400 is arranged logically according to storage priority 408.Storage priority 408 indicates an arrangement of memory from a highpriority associated with a portion of regular area 402 furthest from aportion of cold area 404 to a low priority associated with a portion ofcold area 404 furthest from a portion of regular area 402. Currentlyused objects are typically located in regular area 402 whileinfrequently used objects tend to migrate to cold area 404.

Staging controller 302 of memory manager 300 of FIG. 3 uses popularitydata gathered by a data access frequency method to determine which areaof a memory to convert into a staging area. In one example, memory 400is a regular Java heap. Before the popularity detection method has hadenough time to determine which objects are hot (popular) or cold(unpopular) there is no need to convert a portion of regular area 402and protecting the portion of memory.

With reference to FIG. 5 a block diagram of a memory configuration withstaging area in accordance, with various embodiments of the disclosureis presented. Staging area 500 is an example of a portion of memorymanaged by memory manager 300 of FIG. 3.

Using the previous example of memory 400 of FIG. 4, staging area 500 iscreated from a portion of memory previously defined as regular area 402.The creation of staging area 500 is performed by staging controller 302of memory manager 300 of FIG. 3 using popularity data gathered by a dataaccess frequency method to determine which area of a memory to convertinto staging area 500. In one example, memory 400 is a regular Javaheap, which is converted into staging area 500. In another example,staging area 500 may be created dynamically from a portion of regulararea 402 or logically associated with regular area 402 but physicallycreated on a different storage type and/or device. Storage area 500 maybe created dynamically or statically using pre-allocation in conjunctionwith configuration information.

As time elapses and the popularity detection method obtains andprocesses data access information object access frequency becomesclearer. Memory manager 300 of FIG. 3 in an enhanced managed runtimegroups the seemingly cold objects together into staging area 500, whichis a part of regular area 402 and in one example using a technique ofmemory enable/disable as a tracking mechanism, disables all memoryaccess to staging area 500. Object 502 and object 504, as well as otherobjects comprising a set of objects previously located in regular area402, are located within staging area 500.

Disabling application access to memory comprising the staging area isone example embodiment of implementing the disclosed process.Embodiments of the disclosed process monitor and track all accesses madeto the objects within the staging area using a selected tracking methodfrom a set of tracking methods. For example, modifications may beincorporated into an operating system kernel to track memory accesses tocertain memory ranges more thoroughly. A dedicated access trackinghardware/firmware solution may also be used with a solid-state disk whenused to provide the staging area memory.

With reference to FIG. 6 a block diagram of a memory configuration withstaging area in accordance, with various embodiments of the disclosureis presented. Staging area 500 is an example of a portion of memorymanaged by memory manager 300 of FIG. 3 from which object relocation isplanned.

In one example, when memory access to staging area 500 is disabled, theapplication is completely unaware of the disabled status and continuesto execute as usual. Since cold objects, such as object 502, object 504and object 600, are still being used, although less frequently thanothers, the application attempts to read or write to the cold objects.An application request for a cold object, such as object 504, in stagingarea 500 triggers a memory protection fault using the example.

A signal handler of staging controller 302 of FIG. 3 handling stagingarea 500 catches the memory protection fault, records which object wasaccessed, updates an access frequency count associated with the objectand temporarily allows access to the memory containing the object. Anaccess frequency count is kept for all accessed objects in staging area500 and when an object, such as object 504 is accessed too frequentlythe object is identified and prepared for relocation out of staging area500 into location 602 of regular area 402. In another example, a pageprotection mechanism, memory cache/translation look aside buffer (TLB)frequency data, or hardware assisted profiling may trigger an access foran object in the staging area updating associated frequency of useinformation.

With reference to FIG. 7 a block diagram of a memory configuration withstaging area in accordance, with various embodiments of the disclosureis presented. Staging area 500 is an example of a portion of memorymanaged by memory manager 300 of FIG. 3 from which an object isrelocated to a regular area.

Object 504, accessed too frequently is relocated out of staging area 500into regular area 402. In contrast with the movement of object 504 usualmigrations of objects, for example, according to low access frequencyinformation is indicated as migration direction 700 toward a portion ofcold area 404 furthest from a portion of regular area 402.

With reference to FIG. 8 a block diagram of a memory configuration usedwith a memory manager in accordance, with various embodiments of thedisclosure is presented. In the example, staging area 500 of a portionof memory managed by memory manager 300 of FIG. 3 is no longer required.

The usual migrations of objects, such as object 502 and object 600,according to low access frequency counts, as indicated by migrationdirection 700 of FIG. 7 toward a portion of cold area 404 furthest froma portion of regular area 402 has occurred. Storage area 500 of FIG. 7has been deleted because a requirement for this level of storage nolonger exists. Memory previously allotted to storage area 500 of FIG. 7has been returned to a regular area 402. When storage area 500 is placedin a location other than regular area 402 the storage area is logicallyremoved and awaits reuse.

With reference to FIG. 9 a flowchart of a process for managing a stagingarea in accordance, with various embodiments of the disclosure ispresented. In the example, process 900 is an example of managing astaging area in a portion of memory managed by memory manager 300 ofFIG. 3.

Process 900 begins (step 902) and determines whether candidate coldobjects exist for a staging area (step 904). For example candidate coldobjects may be identified using access frequency information obtainedusing a popularity detection method in which less frequently accessedobjects are viewed as candidates for relocation to less performanceintense memory. Responsive to a determination candidate cold objects donot exist for a staging area process 900 loops back to perform step 902as before.

Responsive to a determination that candidate cold objects exist for astaging area process 900 determines whether the staging area exists(step 906). Responsive to a determination that the staging area does notexist process 900 creates the staging area for identified candidate coldobjects (step 908). The staging area may be created using a default sizeobtained from a data structure associated with a memory manager such asa configuration file or property file. An initial size may be set whichis less than or equal to a size of a cold area. The staging area maylogically be a portion of a regular area of memory in use or anotherportion of a memory physically separate from the regular memory. Thestaging area may be allotted from a different type of memory than thatof the regular area as well.

Responsive to a determination that the staging area exists process 900moves the identified candidate cold objects into the staging area (step910). The identified candidate objects are relocated from the regulararea into the staging area. As stated previously the staging area may bea portion of the regular area or may be a physically different locationand device.

Process 900 tracks application access to memory comprising the stagingarea (step 912). In one example, process 900 disables application accessto memory comprising the staging area as a tracking mechanism forobjects in the staging area. Disabling access to the memory of thestaging area enables applications to continue to use and access objectsin the staging area however a memory access fault will occur on eachapplication request for an object in the staging area. In anotherexample, an application access alerts an access tracking mechanism, suchas a page request, of a desire to use a content of the staging area.

Process 900 updates access frequency information associated with eachspecific object in the staging area. When using another technique ofmonitoring and tracking access to the staging area no further permissionmay be required. In another example, process 900 maintains a datastructure comprising an access list of objects in the staging area,updating the list for each additional object including incrementing afrequency of use indicator, such as an access count, representative of anumber of accesses to an object and a last reference time as accessfrequency information.

Process 900 determines whether the frequency of use information for thespecific object exceeds a predetermined threshold (step 914). Responsiveto a determination that the frequency of use information for thespecific object exceeds a predetermined threshold, process 900 moves thespecific object into the regular area from the staging area (step 916).

Responsive to a determination that the frequency of use information forthe specific object does not exceed a predetermined threshold, process900 determines whether a current time exceeds a predetermined threshold(step 918). The current time is compared with a predetermined value fora time value representing a period or duration since a last access for aspecific object. For example, when the current time is Y and an objecthas been accessed at X time, the difference is time Z and time Z doesnot exceed a predetermined threshold then retain the object otherwiseflush the object. Responsive to a determination that the current timedoes not exceed a predetermined threshold, process 900 terminates (step928).

Responsive to a determination that the current time exceeds apredetermined threshold, process 900 moves remaining objects from thestaging area to a cold area (step 920). Process 900 determines whetherto remove the:staging area (step 922). Responsive to a determination toremove the staging area, process 900 removes the staging (step 924). Thestaging may be physically or logically removed depending on the currentallocation form of the staging area. Responsive to a determination tonot remove the staging area, process 900 terminates thereafter (step928).

When an alternative example of disabling access to the memory is usedprocess 900 is aware application access to the memory comprising thestaging area was disabled. The memory comprising the staging area is nowenabled. The memory previously used as the staging area is returned tothe regular area because the staging area is no longer needed and thestaging area is thus removed.

Thus is presented in an illustrative embodiment a computer-implementedprocess for managing a staging area. The computer-implemented processcreates the staging area for identified candidate cold objects, movesthe identified candidate objects into the staging area, tracksapplication access to memory comprising the staging area and determineswhether frequency of use information for a specific object exceeds apredetermined threshold. Responsive to a determination that thefrequency of use information for the specific object exceeds apredetermined threshold, move the specific object into a regular areaand determine whether a current time exceeds a predetermined threshold.Responsive to a determination that the current time exceeds apredetermined threshold, the computer-implemented process movesremaining objects from the staging area to a cold area.

The flowchart and block diagrams in the figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof code, which comprises one or more executable instructions forimplementing a specified logical function. It should also be noted that,in some alternative implementations, the functions noted in the blockmight occur out of the order noted in the figures. For example, twoblocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved. It will also be notedthat each block of the block diagrams and/or flowchart illustration, andcombinations of blocks in the block diagrams and/or flowchartillustration, can be implemented by special purpose hardware-basedsystems that perform the specified functions or acts, or combinations ofspecial purpose hardware and computer instructions.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present invention has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the invention. Theembodiment was chosen and described in order to best explain theprinciples of the invention and the practical application, and to enableothers of ordinary skill in the art to understand the invention forvarious embodiments with various modifications as are suited to theparticular use contemplated.

The invention can take the form of an entirely hardware embodiment, anentirely software embodiment or an embodiment containing both hardwareand software elements. In a preferred embodiment, the invention isimplemented in software, which includes but is not limited to firmware,resident software, microcode, and other software media that may berecognized by one skilled in the art.

It is important to note that while the present invention has beendescribed in the context of a fully functioning data processing system,those of ordinary skill in the art will appreciate that the processes ofthe present invention are capable of being distributed in the form of acomputer readable medium of instructions and a variety of forms and thatthe present invention applies equally regardless of the particular typeof signal bearing media actually used to carry out the distribution.Examples of computer readable media include recordable-type media, suchas a floppy disk, a hard disk drive, a RAM, CD-ROMs, DVD-ROMs, andtransmission-type media, such as digital and analog communicationslinks, wired or wireless communications links using transmission forms,such as, for example, radio frequency and light wave transmissions. Thecomputer readable media may take the form of coded formats that aredecoded for actual use in a particular data processing system.

A data processing system suitable for storing and/or executing programcode will include at least one processor coupled directly or indirectlyto memory elements through a system bus. The memory elements can includelocal memory employed during actual execution of the program code, bulkstorage, and cache memories which provide temporary storage of at leastsome program code in order to reduce the number of times code must beretrieved from bulk storage during execution.

Input/output or I/O devices (including but not limited to keyboards,displays, pointing devices, etc.) can be coupled to the system eitherdirectly or through intervening I/O controllers.

Network adapters may also be coupled to the system to enable the dataprocessing system to become coupled to other data processing systems orremote printers or storage devices through intervening private or publicnetworks. Modems, cable modems, and Ethernet cards are just a few of thecurrently available types of network adapters.

1.-20. (canceled)
 21. A computer-implemented process for managing astaging area, the computer-implemented process comprising: creating thestaging area for identified candidate cold objects, the staging areabeing a data structure that is logically part of a regular area ofmemory where identified candidate cold objects are relocated in order todecide whether to move the identified candidate cold objects to a coldarea and also to test consequences of moving the identified candidatecold objects; moving the identified candidate cold objects into thestaging area; tracking application access to memory by disabling accessto the memory of the staging area but still allowing the application touse and access the identified candidate cold objects in the stagingarea; determining whether frequency of use information based upon thenumber of memory access faults occurring when the application accessesthe identified candidate cold objects in the staging area when theaccess to the memory of the staging area is disabled for a specificobject exceeds a predetermined frequency threshold; responsive to adetermination that the frequency of use information for the specificobject exceeds the predetermined frequency threshold, moving thespecific object into the regular area of memory from the staging area;determining whether a current time exceeds a predetermined timethreshold; and, responsive to a determination that the current timeexceeds the predetermined time threshold, moving remaining objects fromthe staging area to the cold area, the cold area comprising a relativelyslower physical memory than a physical memory of the regular area ofmemory.
 22. The computer-implemented process of claim 21, whereincreating the staging area for the identified candidate cold objectsfurther comprises: determining whether candidate cold objects exist forthe staging area; responsive to a determination candidate cold objectsexist for the staging area, determining whether the staging area exists;responsive to a determination the staging area does not exist using aportion of the regular area of memory, wherein the memory isrepresentative of a memory used by a managed runtime and wherein thememory is arranged in performance tiers comprising a high performancetier associated with the regular area of memory through to a lowerperformance tier of a cold area and wherein the memory comprises one ofa different types of memory and a same types of memory; and, responsiveto a determination the staging area does exist using the staging area.23. The computer-implemented process of claim 21, wherein the creatingthe staging area for the identified candidate cold objects furthercomprises: tracking access patterns of objects using a selected methodincluding a combination of methods selected from a set of methodsincluding traditional read/write barriers, page protection mechanisms,memory cache and translation look aside buffer (TLB) frequency data, andhardware assisted profiling, wherein tracking information includes thefrequency of use information including an access count incremented as aresult of an access of a respective object in the memory and a time oflast access; gathering information using the frequency of useinformation for each object comprising a set of objects in a regularmemory using a popularity detection method selected from a set ofmethods; and, ranking each object set of objects according to thefrequency of use information to form an access frequency.
 24. Thecomputer-implemented process of claim 21, wherein creating the stagingarea for identified candidate cold objects further comprises: reading aconfiguration data structure containing initialization values; and,creating the staging area of a size determined by an initial value inthe configuration data structure, wherein the initial value represents avalue selected from a predetermined number of objects and a size of acold area.
 25. The computer-implemented process of claim 21, whereinmoving the identified candidate objects into the staging area furthercomprises: updating a time last accessed information associated with theobject.
 26. The computer-implemented process of claim 21, wherein movingremaining objects from the staging area to a cold area furthercomprises; determining whether to remove the staging area; and,responsive to a determination to remove the staging area, removing thestaging area from the memory.
 27. The computer-implemented process ofclaim 21, wherein tracking application access to memory furthercomprises detecting all actual object access.
 28. A computer programproduct for managing a staging area, the computer program productcomprising: a computer recordable-type media containing computerexecutable program code stored thereon, the computer executable programcode comprising: computer executable program code for creating thestaging area for identified candidate cold objects, the staging areabeing a data structure that is logically part of a regular area ofmemory where identified candidate cold objects are relocated in order todecide whether to move the identified candidate cold objects to a coldarea and also to test consequences of moving the identified candidatecold objects; computer executable program code for moving the identifiedcandidate cold objects into the staging area; computer executableprogram code for tracking application access to memory by disablingaccess to the memory of the staging area but still allowing theapplication to use and access the identified candidate cold objects inthe staging area; computer executable program code for determiningwhether frequency of use information based upon the number of memoryaccess faults occurring when the application accesses the identifiedcandidate cold objects in the staging area when the access to the memoryof the staging area is disabled for a specific object exceeds apredetermined frequency threshold; computer executable program code forresponsive to a determination that the frequency of use information forthe specific object exceeds the predetermined frequency threshold,moving the specific object into the regular area of memory from thestaging area; computer executable program code for determining whether acurrent time exceeds a predetermined time threshold; and, computerexecutable program code for responsive to a determination that thecurrent time exceeds the predetermined time threshold, moving remainingobjects from the staging area to the cold area, the cold area comprisinga relatively slower physical memory than a physical memory of theregular area of memory.
 29. The computer program product of claim 28,wherein computer executable program code for creating the staging areafor the identified candidate cold objects further comprises: computerexecutable program code for determining whether candidate cold objectsexist for the staging area; computer executable program code responsiveto a determination candidate cold objects exist for the staging area,for determining whether the staging area exists; computer executableprogram code responsive to a determination the staging area does notexist for using a portion of the regular area of memory, wherein thememory is representative of a memory used by a managed runtime andwherein the memory is arranged in performance tiers comprising a highperformance tier associated with the regular area of memory through to alower performance tier of a cold area and wherein the memory comprisesone of a different types of memory and a same types of memory; and,computer executable program code responsive to a determination thestaging area does exist using the staging area.
 30. The computer programproduct of claim 28, wherein computer executable program code forcreating the staging area for the identified candidate cold objectsfurther comprises: computer executable program code for tracking accesspatterns of objects using a selected method including a combination ofmethods selected from a set of methods including traditional read/writebarriers, page protection mechanisms, memory cache and translation lookaside buffer (TLB) frequency data, and hardware assisted profiling,wherein tracking information includes the frequency of use informationincluding an access count incremented as a result of an access of arespective object in the memory and a time of last access; computerexecutable program code for gathering information using the frequency ofuse information for each object comprising a set of objects in a regularmemory using a popularity detection method selected from a set ofmethods; and, computer executable program code for ranking each objectset of objects according to the frequency of use information to form anaccess frequency.
 31. The computer program product of claim 28, whereincomputer executable program code for creating the staging area foridentified candidate cold objects further comprises: computer executableprogram code for reading a configuration data structure containinginitialization values; and, computer executable program code forcreating the staging area of a size determined by an initial value inthe configuration data structure, wherein the initial value represents avalue selected from a predetermined number of objects and a size of acold area.
 32. The computer program product of claim 28, whereincomputer executable program code for moving the identified candidateobjects into the staging area further comprises: computer executableprogram code for updating a time last accessed information associatedwith the object.
 33. The computer program product of claim 28, whereincomputer executable program code for moving remaining objects from thestaging area to a cold area further comprises: computer executableprogram code for determining whether to remove the staging area; and,computer executable program code responsive to a determination to removethe staging area, for removing the staging area from the memory.
 34. Thecomputer program product of claim 28, wherein computer executableprogram code for tracking application access to memory further comprisescomputer executable program code for detecting all actual object access.35. An apparatus for managing a staging area, the apparatus comprising:a communications fabric; a memory connected to the communicationsfabric, wherein the memory contains computer executable program code; acommunications unit connected to the communications fabric; aninput/output unit connected to the communications fabric; a displayconnected to the communications fabric; and, a processor unit connectedto the communications fabric, wherein the processor unit executes thecomputer executable program code to direct the apparatus to: create thestaging area for identified candidate cold objects, the staging areabeing a data structure that is logically part of a regular area ofmemory where identified candidate cold objects are relocated in order todecide whether to move the identified candidate cold objects to a coldarea and also to test consequences of moving the identified candidatecold objects; move the identified candidate cold objects into thestaging area; track application access to memory by disabling access tothe memory of the staging area but still allowing the application to useand access the identified candidate cold objects in the staging area;determine whether frequency of use information based upon the number ofmemory access faults occurring when the application accesses theidentified candidate cold objects in the staging area when the access tothe memory of the staging area is disabled for a specific object exceedsa predetermined frequency threshold; responsive to a determination thatthe frequency of use information for the specific object exceeds thepredetermined frequency threshold, move the specific object into theregular area of memory from the staging area; determine whether acurrent time exceeds a predetermined time threshold; and, responsive toa determination that the current time exceeds the predetermined timethreshold, move remaining objects from the staging area to the coldarea, the cold area comprising a relatively slower physical memory thana physical memory of the regular area of memory.
 36. The apparatus ofclaim 35, wherein the processor unit executes the computer executableprogram code to create the staging area for the identified candidatecold objects further directs the apparatus to: determine whethercandidate cold objects exist for the staging area; responsive to adetermination candidate cold objects exist for the staging area,determine whether the staging area exists; responsive to a determinationthe staging area does not exist use a portion of the regular area ofmemory, wherein the memory is representative of a memory used by amanaged runtime and wherein the memory is arranged in performance tierscomprising a high performance tier associated with the regular area ofmemory through to a lower performance tier of a cold area and whereinthe memory comprises one of a different types of memory and a same typesof memory; and, responsive to a determination the staging area doesexist, use the staging area.
 37. The apparatus of claim 35, wherein theprocessor unit executes the computer executable program code to createthe staging area for the identified candidate cold objects furtherdirects the apparatus to: track access patterns of objects using aselected method including a combination of methods selected from a setof methods including traditional read/write barriers, page protectionmechanisms, memory cache and translation look aside buffer frequencydata, and hardware assisted profiling, wherein the frequency of useinformation including includes an access count incremented as a resultof an access of a respective object in the memory and a time of lastaccess; gather information using the frequency of use information foreach object comprising a set of objects in a regular memory using apopularity detection method selected from a set of methods; and, rankeach object set of objects according to the frequency of use informationincluding to form an access frequency.
 38. The apparatus of claim 35,wherein the processor unit executes the computer executable program codeto create the staging area for identified candidate cold objects furtherdirects the apparatus to: read a configuration data structure containinginitialization values; and, create the staging area of a size determinedby an initial value in the configuration data structure, wherein theinitial value represents a value selected from a predetermined number ofobjects and a size of a cold area.
 39. The apparatus of claim 35,wherein the processor unit executes the computer executable program codeto move the identified candidate objects into the staging area furtherdirects the apparatus to: update a time last accessed informationassociated with the object.
 40. The apparatus of claim 35, wherein theprocessor unit executes the computer executable program code to moveremaining objects from the staging area to a cold area further directsthe apparatus to; determine whether to remove the staging area; and,responsive to a determination to remove the staging area, remove thestaging area from the memory.